Use a regex to parse filter arguments

This fixes the problem where the filter arguments were naively split on
whitespace.

lib/tree.js

@@ -11,6 +11,10 @@ define(function(require, exports, module) {
 
   var parseProperty = require("./utils/parse_property");
 
+  // This breaks up the filter arguments by space delimited or between quotes,
+  // preserves the whitespace inside strings.
+  var filtersRegex = /[ ]|(['"][^'"]*['"])/;
+
   /**
    * Represents a Tree.
    *
@@ -373,18 +377,18 @@ define(function(require, exports, module) {
       previous = node;
     }
 
-    // Split up the input into space-delimited parts.
-    var parts = input.trim().split(" ");
+    // This regex breaks up either by whitespace or between string quotes.
+    var parts = input.trim().split(filtersRegex).filter(Boolean);
 
-    // The partial name.
+    // The filter name.
     current.value = parts[0];
 
     // If no value, this is an error.
     if (!current.value) {
       throw new Error("Missing valid filter name.");
     }
 
-    // Partials have arguments passed.
+    // Filters have arguments passed.
     current.args = parts.slice(1).map(parseProperty);
 
     return root;